ML101380215
| ML101380215 | |
| Person / Time | |
|---|---|
| Site: | Palo Verde  |
| Issue date: | 04/01/2010 |
| From: | Arizona Public Service Co |
| To: | Division of License Renewal |
| Regner L M, NRR/DLR, 415-1906 | |
| References | |
| TAC ME0254, TAC ME0255, TAC ME0256 | |
| Download: ML101380215 (30) | |
Text
PVNGS License Renewal Application Metal Fatigue Topics April 1, 2010 Discussion Topics*Historical and general background*Metal Fatigue Monitoring Program
- Cycle Counting Questions
- Class 1 Fatigue TLAA Evaluation Process*Future actions
- NRC staff questions Historical and general background Initial development of PVNGS metal fatigue monitoring program*Program required by PVNGS Technical Specification 5.5.5*SYS80-PE-DE "Compilation of NSSS Responses to Design Bases Dynamic
Events for the System 80 Standard Design" established applicable design cycles and their 40-year expected accumulation*Class I metal fatigue analyses incorporated the SYS80-PE-DE limits and in some cases identified additional items of concern Initial development of PVNGS metal fatigue monitoring program*The initial Technical Specification program did not require all UFSAR
transients to be monitored*The UFSAR does not incorporate all of the additional limits (e.g. RCP stud tensioning/de-tensioning) -to be
discussed later in this presentation
- PV staff identified that not all UFSAR transients were being counted *Implemented expanded list of transients in January 1996*ITS upgrade in 1998 established current requirements*Not counted data between '85 and '95 was assumed to be an accumulation of 25% of the design allowed transients in all but a few casesProgram Review -1995
- Actual event counting has been in place since January 1996*Unit 1, 2 and 3 records have now been reviewed for LRA support Performance of cycle counting since January 1996 Metal Fatigue Monitoring Program
- Current methodology:-Cycle counting to ensure design assumptions are not exceeded-Specific component locations are not specified-Exception: Partial cycle (CBF-PC) methodology is used to track spray nozzle
usage Current PVNGS Metal Fatigue Monitoring Program
- LRA development prompted PVNGS staff to revisit the assumptions for 1985 -1995*Recounts of all three units were reported in the response to RAI B3.1-4 (see RAI response Table 3.1-4)-Recount Methodology*Best source selected (logs, MORs, LERs, WOs, interviews)*Validated assumptions Addressing Cycle Count Assumptions
- Recount Methodology-Best source selected (logs, MORs, LERs, WOs, interviews)-Reviewed assumption of 25% accumulated cycles*Actual data*Comparison to '95 -'05 operating history Cycle Recount
- Required by 10 CFR54.21 (c)(1)(iii)*Scope -All Class I components *Methodology:-Based on component locations-Adds SBF for high usage locations (not discussed in this presentation)-Continues cycle counting for "Global"monitoring*Used for low 40-year design CUF*No new industry issues since original design*Industry experience indicates not a problem location-Expands CUF monitoring*CBF-C (CUF based on design cycle)*CBF-PC (CUF based on partial cycle)*CBF-EP (CUF based on event pairing)-Establishes appropriate action limits and corrective actions Enhanced Metal Fatigue Monitoring Program
- SBF methodology (to be determined)*FatiguePro is under evaluation for cycle counting and CBF monitoring*Current manual cycle counting will continue until a suitable software program has been
validated*Enhanced program will be implemented no later than two years prior to the PEO (LRA commitment #39 as revised in Amendment 9)Enhanced Program Status Cycle Counting NRC Questions Cycle Counting RAIs and Amendments*Amendment 3 (annual update)-Added Unit 3 record review results and revised one transient total to replace an
estimate with data-Revised current program action limit discussion to avoid confusion with the
enhanced program limits-Minor clarifications were included in the AMP OE discussion Cycle Counting RAIs and Amendments (continued)*Amendment 9 (result of RAI B3.1-1 thru 8)-RAI B3.1-4 response provided the individual unit cycle totals from best available sources-Corrected typographical errors
-Included enhanced monitoring implementation schedule-Committed to selection of a suitable SBF methodology-Clarified cycle projection methodology Cycle Counting RAIs and Amendments (continued)
Most recent cycle count related DRAI set (DRAI 4.3-1 thru 9-DRAI 4.3-1 Transients projected to exceed 40-year limits*Projections are conservative and may not be reached*10CFR54.21(c)(1)(iii) permits aging management for TLAAs that are not validated or projected for the PEO*NUREG 1800 paragraph 4.3.3.1.1.
3 permits the use of GALL programs for aging management*NUREG 1801 Vol2 AMP X.M1 allo ws use of this program to manage aging and recommends "no further evaluation"if this program is selected to satisfy 10CFR54.21(c)(1)(iii)*PVNGS took no exceptions to X.M1 and concludes fatigue reanalyses are not required bas ed on projections . Corrective action will be initiated if needed based on program action limits Cycle Counting RAIs and Amendments (continued)*DRAI 4.3-1 LRA Transient projection methodology-Presented for information only -Concept of a worst case bounding unit
-Conservative Assumptions*Highest unit total was used for '85-'95 and for '95-'05*Lowest operating years was used for accumulation rate*42 years were used for projecting and added to above*'Zero accumulation'assumed to be linear times 22/40-If not expected still assumed 1 event Cycle Counting RAIs and Amendments (continued)*DRAI 4.3-2 Global monitoring criteria does not seem consistent-Exceptions are explained in LRA table notes*DRAI 4.3-3 Clarify the CBF-PC method
- DRAI 4.3-4 Program action limits (see commitment #39)
- DRAI 4.3-5 Some cycles do not agree with the UFSAR-Some are derived from UFSAR sections other than 3.9.1-Some come from specific analyses (e.g. RCP studs)-Addition of cycles to the UFSAR is under consideration Cycle Counting RAIs and Amendments (continued)*DRAI 4.3-6 25% cycle assumption-Review of best source data was presented in the response to RAI B3.1-4-Compared assumption to actual data from recount efforts or data from '95-'05-Result:*Four assumptions of 25% cycle accumulation are being reviewed: Rx Trip, Load Reject, Turbine Trip w/o Rx
Trip and Depressurization by MSSV at 100% power*Remaining 25 % assumptions are conservative Cycle Counting RAIs and Amendments (continued)*DRAI 4.3-7 Not all cycles were recounted-Some had accurate data and did not require recount-Some were not significant (e.g. plant loading at 5%/min)-Some could not be recovered so the 25%
assumption was used and validated from '95-
'05 data Cycle Counting RAIs and Amendments (continued)*DRAI 4.3-8 Questioned an incorrect table note (had been corrected in Amendment
9)*DRAI 4.3-9 Some cycles are not included in the UFSAR (similar to DRAI 4.3-5)-Some come from specific analyses (e.g. RCP studs)-Addition of cycles to the UFSAR is under consideration Class 1 Fatigue TLAA Evaluation Process -LRA Section 4.3.2
- Identify TLAAs and Affected Components-SRP Guidance, Industry Experience, CLB Search*Retrieve Component Current Licensing and Design Basis Documents (CLB and CDB)*Evaluate and Summarize CDB TLAAs-Analysis Results -Analyzed Locations, CUFs, etc.
-Effects of Modification, Analysis, and Op. History
-Effects of Differences in Analysis Methods-Identify Disposition Class 1 Fatigue TLAA Evaluation Process
- SRP Guidance-NUREG-1800 Sect. 4.3 and Tables for Class 1-Based on ASME III Subsection NB and NG and Industry Experience*Industry Experience-Examples:-Other LRAs-NRC and NSSS vendor Bulletins, Notices, etc.*CLB Search-Word Search of CLB (FSAR, Docketed Reports, Letters, etc.)-Confirm applicability to Palo Verde-Identify other plant-specific TLAAs Identify TLAAs and Affected Component s
- Research and Summarize History of CLB-Confirm Current Licensing Basis*Research Design and Analysis History-Confirm Current Design Basis-TLAAs are analyses , are therefore part of the CDB-TLAAs are usually bases of the CLB ("incorporated by reference") rather than included verbatim Retrieve Component Current Licensing and Design Basis Documents (CLB and CDB)
- Analysis Results-All TLAA Results (e.g., all reported fatigue summaries)-All Analyzed Locations
-Tabulated for Complex Components*Effects of Modification, Analysis, and Operating History -
Examples:-Instrument Nozzle Half-Nozzle and MNSA Repairs (Several LRA Sections)-Pressurizer Surge Line Thermal Stratification (LRA Section 4.3.2.9)-Unit 2 Head Vent Repair -high part-life CUF, head replaced Fall 2009 (LRA p. 4.3-34)
Evaluate and Summarize CDB TLAAs
- Identify Disposition-Based on Analysis History, Results, and Methods*10 CFR 54.21(c)(1)(i) -If simple design life or cycle ratios, etc., confirm adequate margin at 60 years*10 CFR 54.21(c)(1)(iii) -Used in most other cases-Requires Aging Management*10 CFR 54.21(c)(1)(ii) -Reanalysis performed Evaluate and Summarize CDB TLAAs (Continued)
- Identify Disposition (Continued)-10 CFR 54.21(c)(1)(iii) monitoring methods are described in LRA 4.3.1, summarized by monitored
location in Table 4.3-4-Details of 10 CFR 54.21(c)(1)(iii) monitoring methods are location and analysis-specific.
Examples:*Global -monitor transients *Cycle-based fatigue (CBF) -moni tor transients, possible CUF impacts*Stress-based fatigue (SBF) -i mpact of transients require reevaluation of CUF Evaluate and Summarize CDB TLAAs (Continued)
NRC Staff Questions*Have we answered the questions and issues stated in this presentation?*Does the staff have additional questions with respect to cycle counting or the
PVNGS approach to metal fatigue?*Review action items
- Future topics Thank you for your participation